Configure default model is not used in ACP

[wittjosiah]

Description

Given the following config:

{
  "$schema": "https://opencode.ai/config.json",
  "model": "anthropic/claude-sonnet-4-5-20250929"
}

When using opencode cli the model defaults to Sonnet 4.5 on startup. However, when using opencode via acp in zed the default model is always OpenCode Zen/Big Pickle.

OpenCode version

1.0.35

Steps to reproduce

1. Set default model in config
2. Open Zed
3. Create new OpenCode thread

Screenshot and/or share link

No response

Operating System

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Terminal

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[github-actions]

This issue might be related to existing issues with model configuration in different contexts. Please check:

• custom agents pick up default model instead of specified one, until toggled #3571: custom agents pick up default model instead of specified one, until toggled (closed - dealt with similar config not being respected)
• ACP in Zed: duplicated models #3400: ACP in Zed: duplicated models (open - shows there are known ACP-specific model issues)

However, your specific case of config default model being ignored in ACP appears to be a distinct issue from these. Feel free to ignore if none of these address your specific case.

[rekram1-node]

Oh ill fix that

[rekram1-node]

/oc can u fix this, look in acp/agent.ts i think there is a condition out of order that is causing opencode big pickle to override the defaults set from the users config. There is a chance we aren't reading model from the Config.get() call if so fix that

This happens when the server is initialized I believe, but it could be happening on session load, in either case fix

[opencode-agent]

Created PR #4006

opencode session  |  github run